Journal
JOURNAL OF BACTERIOLOGY
Volume 188, Issue 7, Pages 2502-2511Publisher
AMER SOC MICROBIOLOGY
DOI: 10.1128/JB.188.7.2502-2511.2006
Keywords
-
Categories
Funding
- NCI NIH HHS [P30 CA042014, 5P30 CA42014] Funding Source: Medline
- NIBIB NIH HHS [R01-EB2041] Funding Source: Medline
- NIGMS NIH HHS [R01-GM64663, R01-GM64664, R01 GM064664] Funding Source: Medline
Ask authors/readers for more resources
FliN is a major constituent of the C ring in the flagellar basal body of many bacteria. It is present in > 100 copies per flagellum and together with FliM and FliG forms the switch complex that functions in flagellar assembly, rotation, and clockwise-counterclockwise switching. FliN is essential for flagellar assembly and switching, but its precise functions are unknown. The C-terminal part of the protein is best conserved and most important for function; a crystal structure of this C-terminal domain of FliN from Thermotoga maritima revealed a saddle-shaped dimer formed mainly from P strands (P. N. Brown, M. A. A. Mathews, L. A. Joss, C. P. Hill, and D. F. Blair, J. Bacteriol. 187:2890-2902, 2005). Equilibrium sedimentation studies showed that FliN can form stable tetramers and that a FliM(1)FliN(4) complex is also stable. Here, we have examined the organization of FliN subunits by using targeted cross-linking. Cys residues were introduced at various positions in FliN, singly or in pairs, and disulfide cross-linking was induced by oxidation. Efficient cross-linking was observed for certain positions near the ends of the dimer and for some positions in the structurally uncharacterized N-terminal domain. Certain combinations of two Cys replacements gave a high yield of cross-linked tetramer. The results support a model in which FliN is organized in doughnut-shaped tetramers, stabilized in part by contacts involving the N-terminal domain. Electron microscopic reconstructions show a bulge at the bottom of the C-ring whose size and shape are a close match for the hypothesized FliN tetramer.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available